glaciers

A new study released by University of Colorado at Boulder’s Institute of Arctic and Alpine Research says that overall sea level rise from climate change may be lower than originally predicted. Many researchers believe that sea levels could increase 20 to 30 feet by the end of the century. The team at Boulder modeled various scenarios relating to melting glaciers and ice caps, as well as thermal expansion of water, and believe the most plausible scenario shows a rise of only 3 to 6 feet by the end of the century.

The team began the study by postulating future sea level rise at about 2 meters by 2100 produced only by Greenland, said Pfeffer. Since rapid, unstable ice discharge into the ocean is restricted to Greenland glacier beds based below sea level, they identified and mapped all of the so-called outlet glacier “gates” on Greenland’s perimeter — bedrock bottlenecks most tightly constraining ice and water discharge.

“For Greenland alone to raise sea level by two meters by 2100, all of the outlet glaciers involved would need to move more than three times faster than the fastest outlet glaciers ever observed, or more than 70 times faster than they presently move,” said Pfeffer. “And they would have to start moving that fast today, not 10 years from now. It is a simple argument with no fancy physics.”

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Considering all major sources of sea level rise, including Greenland, Antarctica, smaller glaciers and ice caps and the thermal expansion of water, the team’s most likely estimate of roughly 3 to 6 feet by 2100 is still potentially devastating to huge areas of the world in low-lying coastal areas, said Pfeffer.

Some scientists have theorized that continuing warming trends in Greenland and Antarctica could warm the Earth by 4 degrees F over the present by 2100. The last time that happened, roughly 125,000 years ago during the last interglacial period, glacier changes raised sea level by 12 to 20 feet or more. But the time scale is poorly constrained and may have required millennia, Pfeffer said.

“In my opinion, some of the research out there calling for 20 or 30 feet of sea rise by the end of the century is not backed up by solid glaciological evidence,” said Pfeffer.

[Via Eurekalert]

A glacier inside the crater of Mount St. Helens is apparently one of the few glaciers in the world that is actually growing. Measurements and observations by scientists from the USGS show that the volume of ice is increasing and that two “glacial arms” wrapping around the new lava dome (formed as a result of the eruption beginning in 2004) will eventually meet.

“We’ve all been surprised at how little melt has actually happened,” said Carolyn Driedger, a hydrologist with the U.S. Geological Survey in Vancouver. “Intuitively, you would certainly expect more snow and ice melt.”

Meanwhile, two severed “arms” of the glacier have been shoved around the old lava dome and northward down the crater slope — covering an area roughly the size of downtown Portland. The ends of the two arms, each looming 60 to 130 feet in height, lately have moved closer together in a kind of geological embrace.

[Via The Columbian]

Rocks and boulders collected from glaciers in Antarctica could help scientists determine glacial behavior and impacts of climate change along the West Antarctic Ice Sheet.

Scientists from the British Antarctic Survey, Durham University and the Alfred Wegener Institute for Polar and Marine Research collected football (soccer one can assume?) sized boulders. It sounds like the researchers used a form of cosmogenic dating to determine how long the boulders had been exposed to sunlight.

Image credit: NASA

Initial results show that Pine Island Glacier has ‘thinned’ by around 4 centimetres per year over the past 5,000 years, while Smith and Pope Glaciers thinned by just over 2 cm per year during the past 14,500 years. These rates are more than 20 times slower than recent changes: satellite, airborne and ground based observations made since the 1990s show that Pine Island Glacier has thinned by around 1.6 metres per year in recent years.

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Co-author Dr Mike Bentley from the University of Durham said, “When rocks are left high and dry by thinning glaciers they are exposed to high energy cosmic rays which bombard the rock. This creates atoms of particular elements that we can extract and measure in the laboratory - the longer they have been exposed the greater the build-up of these elements. The discovery that we can place a fix on when rocks were left behind by the ice has revolutionised our understanding of how the Antarctic ice sheet has behaved in the past.”